1. Field of the Invention
The invention relates to a technology for controlling the ignition of a spark ignition internal combustion engine.
2. Description of the Related Art
For example, Japanese Patent Application Publication No. 2000-240547 (JP-A-2000-240547) describes a technology that changes the ignition time of a spark ignition internal combustion engine beyond the MBT (Minimum spark advance for Best Torque) so as to accelerate the increase of the coolant temperature and increase the efficiency of the warming-up of the internal combustion engine.
According to the technology described above, however, because exhaust emissions are not taken into consideration although the warming-up efficiency is, the technology may fail to comply with exhaust-emission regulations that are becoming stricter than ever.